Design of the VAX 4000 Model 400, 500, and 600 Systems

The design of Digital's NVAX CPU chip provided the opportunity to bring RISC-class performance to deskside CISC VAX computer systems. The new VAX 4000 Model 400, 500, and 600 low-end systems take full advantage of the performance capabilities of the NVAX microprocessor. The three systems offer from two to four times the performance of the previous top-ofthe-line VAX 4000 Model 300 system in the same deskside enclosure. To achieve this increased performance, Digital's systems engineers designed a new high-performance memory controller chip as part of the CPU module, whose basic design is shared by the three systems. In addition, a highperformance memory module and a VLSI bus adapter chip were designed.